Malignancy index based on flow cytometry and histology for renal cell carcinomas and its correlation to prognosis.

Fifty-five human renal cell carcinomas, removed by nephrectomy, were classified using flow cytometry and histology. The parameters obtained by flow cytometry were DNA index, fractions of cells in the phases, and fractions of tumor cells versus normal cells. From histology, the routine classification of tumor structure and morphology were obtained, and a nuclear grading according to Arner et al. (Acta Chir Scand [Suppl] 346:1-12, 1965) was determined. All parameters including tumor stage according to Robson et al. (J Urol 101:297-301, 1969) were subjected to discriminant analysis in order to define a malignancy index. The patients were divided into two groups with good and poor prognosis (low and high risk). Those patients who were free of multiple metastases in 2 years and more after nephrectomy were assigned to the group "good prognosis"; those who developed multiple metastases for 2 years represented the "poor prognosis" group. The malignancy index determined by discriminant analysis yielded 91% correct predictions of prognosis.